Spatial Analysis with Rasters and ArcGIS Model Builder

Evgeny Noi

September 6, 2021

Raster Processing Basics

Please refer to Neon Project for more details and R-code examples. Many definitions came from USGS and geodetics.com.

Terminology

A DEM (Digital Elevation Model) Represents the bare-Earth surface, removing all natural and built features;
A DSM (Digital Surface Model) captures both the natural and built/artificial features of the environment, as shown below;
A DTM (Digital Terrain Model) typically augments a DEM, by including vector features of the natural terrain, such as rivers and ridges. A DTM may be interpolated to generate a DEM, but not vice versa.
Hillshade: Shaded relief, or hillshading, is a technique where a lighting effect is added to a map based on elevation variations within the landscape.

Terrain Model

## class      : RasterLayer 
## dimensions : 5060, 4299, 21752940  (nrow, ncol, ncell)
## resolution : 1, 1  (x, y)
## extent     : 254570, 258869, 4107302, 4112362  (xmin, xmax, ymin, ymax)
## crs        : +proj=utm +zone=11 +datum=WGS84 +units=m +no_defs 
## source     : SJER2013_DTM.tif 
## names      : SJER2013_DTM

## Range:

## [1] 228.10 518.66

Projections Refresher

Plotting raster

Same picture, more pixels

Filter values and plot

Use colors from terrain palette

Would be nice to add a legend

Fewer breaks

Using spplot R-library for plotting

Creating more aesthetic maps with layering and shadowing

ArcGIS can do better

Mapping flood risk

Follow along this 4hr tutorial to generate this:

Create custom hillshade

Follow along this 1hr tutorial to generate this:

Map hurrican storm surges

Follow along this 0.5hr tutorial to generate this:

Other ArcGIS Pro resources

Intro to working with raster here
Find out how to work with rasters and ArcGIS Pro here

More advanced methods on raster data

Raster calculations (DSM-DTM)
Working with multiband rasters
Working with time-series rasters

ArcGIS Model Builder

Why use model builder?

repetitive and tedious tasks
reproducibility

Automating

Writing a program (Classical text-based programming versus visual programming)

ModelBuilder is a visual programming language for building geoprocessing workflows. Geoprocessing models automate and document your spatial analysis and data management processes. You create and modify geoprocessing models in ModelBuilder, where a model is represented as a diagram that chains together sequences of processes and geoprocessing tools, using the output of one process as the input to another process.

ModelBuilder in ArcGIS Pro allows you to do the following:

Build a model by adding and connecting data and tools.
Iteratively process every feature class, raster, file, or table in a workspace.
Visualize your workflow sequence as an easy-to-understand diagram.
Run a model step by step, up to a selected step, or run the entire model.
Make your model into a geoprocessing tool that can be shared or can be used in Python scripting and other models.

The model runs the following tools in sequence:

Select Layer By Attribute—Select the correct vegetation type from a Vegetation map layer.
Buffer—Create areas within a distance of 1,500 feet around major roads.
Erase—Erase the buffer areas from the selected vegetation areas.
Intersect—Overlay the output of the Erase tool with other map layers, including slope, elevation, and climate. This identifies the areas that meet all criteria.